main/syslog: Allow dynamic logs, such as security events, to log to the syslog

The security event log uses a dynamic log level (SECURITY) that is registered
with the Asterisk logging core. Unfortunately, the syslog would ignore log
statements that had a dynamic log level associated with them. Because the
syslog cannot handle ad hoc dynamic log levels, this patch treats any dynamic
log entries sent to the syslog as logs with a level of NOTICE.

ASTERISK-20744 #close
Reported by: Michael Keuter
Tested by: Michael L. Young, Jacek Konieczny
patches:
  asterisk-20744-syslog-dynamic-logging_trunk.diff uploaded by Michael L. Young (license 5026)
........

Merged revisions 430506 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@430507 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/syslog.h

@@ -28,6 +28,8 @@
 extern "C" {
 #endif
 
+#define ASTNUMLOGLEVELS 32
+
 /*!
  * \since 1.8
  * \brief Maps a syslog facility name from a string to a syslog facility

main/syslog.c

@@ -163,8 +163,16 @@ static const int logger_level_to_syslog_map[] = {
 
 int ast_syslog_priority_from_loglevel(int level)
 {
+	/* First 16 levels are reserved for system use.
+	 * Default to using LOG_NOTICE for dynamic logging.
+	 */
+	if (level >= 16 && level < ASTNUMLOGLEVELS) {
+		return LOG_NOTICE;
+	}
+
 	if (level < 0 || level >= ARRAY_LEN(logger_level_to_syslog_map)) {
 		return -1;
 	}
+
 	return logger_level_to_syslog_map[level];
 }